I very luckily got landed with a: Phidgets Board 8/8/8 (1018) Lanbao PR18S-TM10DNO Photoelectric Tripwire Sensor (3525) I wired the Tripwire sensor to the Phidget board as described in the wiring diagram and as shown in the video: I connected the USB cable from the Phidgets Board to the USB port on a Raspberry Pi… Read more »
Posts By: jonny
Batch Auto-Levels on Images
I had a thousand image files the kids had photographed when creating a stop motion video. An ‘auto-levels’ on many of the images was required to brighten them up so at the command line I used the following (with ImageMagick already installed of course):
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for FILE in $(ls /home/jonny/tmp/stopmotion/*.JPG); do convert -auto-level $FILE /home/jonny/tmp/stopmotion-fixed/$(basename $FILE) ; done |
ImageMagick is impressive – getting through each image in under… Read more »
Customise Yakuake Tabs On Start
I’ve been recommending the slide-down terminal Yakuake to people for some time now and I couldn’t live without it myself. Although I use Cinnamon as a desktop I much prefer Yakuake over Guake and can live with the extra RAM usage of the KDE libraries. When logging in I wanted to have tabs created for… Read more »
Bleeding Edge PHP on CentOS 7
The PHP packages in the base / epel repositories are very conservative. To opt for something more current the REMI repo can be used. Install the remi-release package (info) first:
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wget http://rpms.famillecollet.com/enterprise/remi-release-7.rpm rpm -ivh remi-release-7.rpm |
This will create the remi specific repo files in the /etc/yum.repo.d directory, specifically:
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remi-php70.repo remi.repo remi-safe.repo |
To install later PHP versions alongside your current PHP version… Read more »
Discourse CentOS – which: no docker.io in
This must be my second or third attempt at Discourse having given up several times before and I may well find reasons to avoid it again. The Discourse advice of just use Ubuntu or using DigitalOcean doesn’t cut it for me. One of the problems I ran into today (after following these docker/discourse instructions) was… Read more »
Arduino Serial Port Menu Greyed Out
On Linux Mint (Ubuntu) I had installed the Arduino IDE from the repository and that had installed version 1.0.5. Despite setting the permissions on the Arduino USB device, the ‘Serial Port’ option in the IDE menu was greyed out and would not allow for selecting the device – it thus defaulted to using COM1 –… Read more »
Resetting Drained Slurm Node
After barking up the wrong tree for a while I discovered via StackExchange how to reset a Slurm Node reporting as drained. Run the scontrol command then update the node as shown in the following example commands (amend the word jacob here to the name of your node):
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[root@machine]# scontrol scontrol: update NodeName=jacob State=DOWN Reason="undraining" scontrol: update NodeName=jacob State=RESUME scontrol: show node jacob NodeName=jacob Arch=x86_64 CoresPerSocket=12 CPUAlloc=0 CPUErr=0 CPUTot=96 CPULoad=0.01 Features=Xeon,IVB Gres=(null) NodeAddr=jacob NodeHostName=jacob Version=15.08 OS=Linux RealMemory=257668 AllocMem=0 FreeMem=254573 Sockets=4 Boards=1 State=IDLE ThreadsPerCore=2 TmpDisk=49971 Weight=1 Owner=N/A BootTime=2015-12-19T10:13:10 SlurmdStartTime=2015-12-26T21:52:49 CapWatts=n/a CurrentWatts=0 LowestJoules=0 ConsumedJoules=0 ExtSensorsJoules=n/s ExtSensorsWatts=0 ExtSensorsTemp=n/s scontrol: quit |
MySQL GRANT SELECT on a demo database to all users
I needed to give all students read access to a demo database and did so with: mysql> GRANT SELECT ON gameofthrones.* TO ”@localhost; Query OK, 0 rows affected (0.00 sec) mysql> FLUSH PRIVILEGES; Query OK, 0 rows affected (0.01 sec)
Kerberos Keytab File Creation on Ubuntu
To create a kerberos keytab file on Ubuntu and with the kerberos packages installed (e.g. sudo apt-get install krb5-user )
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root@jmcc02:~# ktutil ktutil: addent -password -p myusername@DOMAIN.TLD.COM -k 1 -e RC4-HMAC Password for myusername@DOMAIN.TLD.COM: ktutil: wkt username.keytab ktutil: quit root@jmcc02:~# |
After completing those steps there should be a keyfile created in the current directory. That keytab file can be used instead of using a password. For example:
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/usr/bin/kinit myusername@DOMAIN.TLD.COM -k -t /root/username.keytab |
Apache: unable to open logs
In the annals of “Everyday is a learning day”. I have an Apache server hosting student websites, and the number of websites grew to over 700 within a day and Apache was complaining with error:
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unable to open logs |
It took a little while to narrow down the problem as I assumed there was a path that did… Read more »
